Baricitinib is a Janus kinase (JAK) inhibitor. It is chemically designated as {1-(ethylsulfonyl)-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]azetidin-3-yl}acetonitrile, having the structure as depicted in Formula I.

U.S. Pat. No. 8,158,616 discloses a process for the preparation of baricitinib comprising the reaction of 2-(1-(ethylsulfonyl)azetidin-3-ylidene)acetonitrile of Formula II with 4-(1H-pyrazol-4-yl)-7H-pyrrolo[2,3-d]pyrimidin-7-yl methyl pivalate of Formula III to provide an intermediate of Formula IV, followed by deprotection of the intermediate of Formula IV to obtain baricitinib of Formula I, as depicted in Scheme I below:

The process disclosed in U.S. Pat. No. 8,158,616 requires a deprotection step in the last stage of the synthesis, which adds to the cost of the overall synthesis.
Thus, there exists a need for an alternate, cost-effective, and industrially advantageous process for the preparation of baricitinib.